title: Microbial communities of deep-sea methane seeps at Hikurangi continental margin (New Zealand).
abstract: The methane-emitting cold seeps of Hikurangi margin (New Zealand) are among the few deep-sea chemosynthetic ecosystems of the Southern Hemisphere known to date. Here we compared the biogeochemistry and microbial communities of a variety of Hikurangi cold seep ecosystems. These included highly reduced seep habitats dominated by bacterial mats, partially oxidized habitats populated by heterotrophic ampharetid polychaetes and deeply oxidized habitats dominated by chemosynthetic frenulate tubeworms. The ampharetid habitats were characterized by a thick oxic sediment layer that hosted a diverse and biomass-rich community of aerobic methanotrophic Gammaproteobacteria. These bacteria consumed up to 25% of the emanating methane and clustered within three deep-branching groups named Marine Methylotrophic Group (MMG) 1-3. MMG1 and MMG2 methylotrophs belong to the order Methylococcales, whereas MMG3 methylotrophs are related to the Methylophaga. Organisms of the groups MMG1 and MMG3 are close relatives of chemosynthetic endosymbionts of marine invertebrates. The anoxic sediment layers of all investigated seeps were dominated by anaerobic methanotrophic archaea (ANME) of the ANME-2 clade and sulfate-reducing Deltaproteobacteria. Microbial community analysis using Automated Ribosomal Intergenic Spacer Analysis (ARISA) showed that the different seep habitats hosted distinct microbial communities, which were strongly influenced by the seep-associated fauna and the geographic location. Despite outstanding features of Hikurangi seep communities, the organisms responsible for key ecosystem functions were similar to those found at seeps worldwide. This suggests that similar types of biogeochemical settings select for similar community composition regardless of geographic distance. Because ampharetid polychaetes are widespread at cold seeps the role of aerobic methanotrophy may have been underestimated in seafloor methane budgets.
authors.affiliation: HGF MPG Group for Deep Sea Ecology and Technology, Max Planck Institute for Marine Microbiology, Bremen, Germany ; Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: S Emil
authors.initials: SE
authors.lastname: Ruff
authors.forename: Julia
authors.initials: J
authors.lastname: Arnds
authors.forename: Katrin
authors.initials: K
authors.lastname: Knittel
authors.forename: Rudolf
authors.initials: R
authors.lastname: Amann
authors.forename: Gunter
authors.initials: G
authors.lastname: Wegener
authors.forename: Alban
authors.initials: A
authors.lastname: Ramette
authors.forename: Antje
authors.initials: A
authors.lastname: Boetius
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001105:Archaea / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D001483:Base Sequence; D016000:Cluster Analysis; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D020564:Deltaproteobacteria / Q000235:genetics / Q000378:metabolism; D017753:Ecosystem; D005453:Fluorescence; D020563:Gammaproteobacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D015723:Gene Library; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology*; D017404:In Situ Hybridization, Fluorescence; D008697:Methane / Q000378:metabolism*; D064307:Microbiota / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D009520:New Zealand; D010140:Pacific Ocean; D010802:Phylogeny; D011077:Polychaeta / Q000502:physiology*; D017422:Sequence Analysis, DNA
chemical_list: D021903:DNA, Ribosomal Spacer; D008697:Methane